Abstract
In this paper we investigate how the Reionization process is affected by early galaxy formation in different cosmological scenarios. We use a semi-analytic model with suppressed initial power spectra to obtain the UV Luminosity Function in thermal Warm Dark Matter and sterile neutrino cosmologies. We retrace the ionization history of intergalactic medium with hot stellar emission only, exploiting fixed and variable photons escape fraction models (fesc). For each cosmology, we find an upper limit to fixed fesc, which guarantees the completion of the process at z<6.7. The analysis is tested with two limit hypothesis on high-z ionized hydrogen volume fraction, comparing our predictions with observational results.
Highlights
The Epoch of Reionization (EoR) marked a fundamental phase transition in the history of the Universe, during which the Intergalactic Medium (IGM) became transparent to UV photons
A “late Reionization” scenario emerges from the combination of several probes: the Thomson scattering optical depth of cosmic microwave background (CMB) photons on the free electrons in the IGM [1,2,3]; the absorption due to neutral intergalactic hydrogen and the appearance of Gunn-Peterson thought in the spectra of distant QSOs [4,5]; the evolution of the Lyman-α emitters (LAEs) luminosity function [6]; and the decreasing of the abundance of the Lyman-Break-Galaxies (LBGs) at z > 6 [6,7]
In this paper we have studied how the suppression of the continue (WDM) and the dashed (CDM) power spectrum due to particles free streaming can have macroscopic consequences, via a late galaxy formation, on the Reionization of IGM
Summary
The Epoch of Reionization (EoR) marked a fundamental phase transition in the history of the Universe, during which the Intergalactic Medium (IGM) became transparent to UV photons This phase transition is most likely caused by the energetic photons emitted by the first sources of light ever formed, i.e., galaxies and AGNs. A “late Reionization” scenario emerges from the combination of several probes: the Thomson scattering optical depth of cosmic microwave background (CMB) photons on the free electrons in the IGM [1,2,3]; the absorption due to neutral intergalactic hydrogen and the appearance of Gunn-Peterson thought in the spectra of distant QSOs [4,5]; the evolution of the Lyman-α emitters (LAEs) luminosity function [6]; and the decreasing of the abundance of the Lyman-Break-Galaxies (LBGs) at z > 6 [6,7]. The study of Reionization is strongly related to the comprehension of cosmological framework in which cosmic structures form and grow
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